There is no function in the driver for this as it just returns raw data.

What you can do is implement a moving average filter using 256 samples to get 4 additional bits of resolution, as shown in the table on the link.Just read in 256 samples and average them replacing sample 1, then move to sample 2 and average the next 256 values and replace sample 2. Repeat this through the data set and you will have your 16 bit data.